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Patented Oct. 12, i954 California Research Corporation, San Fran cisco,Caiif., a corporation of Delaware No Drawing. Application December 11,1952,

5 Claims. I

The present invention relates to anionic syn thetic detergentcompositions. More particularly, it relates to improved anionic alkylsulfate detergent compositions capable of producing dense, stable foamwhen aqueous solutions of these compositions are employed inconventional concentrations for household or commercial laundering.

Small scale users of synthetic anionic detergents insist that thedetergent products be capable of producing substantial lather or foamand that this foam remain stable during the washing process. The averagehousewife persists in the belief that satisfactory detergency andformation of copious foam go hand in hand and seeks detergent productswhich would produce rich, dense lathers or foams constituted by littlebubbles and on contact with the hand would give the feeling of acream-like consistency of soap suds. This persistent prejudice isresponsible for the slow customer acceptance of synthetic anionicdetergents for laundering purposes, particularly in the home, since manyefiicient detergents have but little foaming power, and also since thefoam produced by them is rather poor in texture and lacy, and does notpossess sufficient stability.

In U. S. Patents Nos. 2,166,314 and 2,166,315, Martin proposed to addhigher saturated C8-Cl8 aliphatic alcohols to compositions containingsulfated alcohol detergents for the purpose of improving the sudsingproperties of th se compositions. However, such an addition, whileimproving the sudsing ability, brings about certain disadvantages,namely: (1) a relatively large portion of the aliphatic alcohols addedto the neutralized slurry of alkyl sulfate detergent lost in thesubsequent drying of the slurry; (2) a fatty odor characteristic ofthese alcohols is imparted to the product.

I have now found that desirable foaming characteristics and satisfactoryfoam stability can be impart-ed to detergent compositions which containas their surface-active ingredient an anionic water-soluble salt of astraight-chain 312-022 alkyl sulfuric acid, by adding to thesecompositions a minor amount of a salt of a primary C12-Ci8straight-chain alkyl amine and an organic acid from the group consistingof higher C12-C1s saturated fatty acids, Gil-C18 monoalkyl benzenesulfonic acids and Ciz-Cis straight-chain monoalkyl sulfuric acids. Ingeneral, from about 0.5 to about 10% by weight of this salt, based onthe solid constituents of the detergent composition, sufiices to securea satisfactory, stable foam.

When aqueous solutions of the detergent com- Serial No. 325,441

22 positions containing as their surface-active ingradient saidwater-soluble salt of a C12C22 straight-chain alkyl sulfuric acid andthe aforementioned alkyl ammonium salt additive are employed to washfabrics, in concentrations conventional in the laundering practice (0.1to 0.4%),

they produce a rich, creamy foam of densely agglomerated small bubblesreadily recognizable by squeezing through the fingers. This foam retainsits stability for relatively long periods of time, and the detergency ofthe wash solutions containin these detergent compositions not only isunaffected by the presence of the alkyl aininonium salt additive whichpromotes and stabilizes the foam, but frequently is enhanced thereby.

As stated hereinbefore, the detergent compositions of my inventioncapable of producing satisfactory, stable foam contain as theirsurface-- active ingredient water-soluble salts of an alkyl sulfuricacid in which the hydrophobic alkyl radical is constituted by a straightcarbon to carbon chain of 12 to 22 carbon atoms.

The term a salt of an alkyl sulfuric acid, as employed in thisspecification, includes alkyl sulfates, and alphaand beta-hydroxyalkylsulfates. In all of these alkyl sulfates, the hydrophilic group occupiesthe terminal position on the carbon chain.

ihe term a water-soluble salt as used in this specification is intendedto include all watersoluble detergent salts of C12-C22 allryl sulfuricacids, namely, inorganic alkali metal salts, alkaline earth metal salts,e. g., calcium and magnesium; ammonium salts; alkyl and allzylol an1-moniurn salts, e. g,, triethanol ammonium salts.

Generally speaking, the N-n-alkyl ammonium salts which promote foamformation and stabilize the foam of alkyl sulfate detergents in accordance with the invention, can be formed by reacting the organic base, i.e., primary normal Q2 31;

alkyl amine, with an acid from the group consisting of higher saturatedClE-CZS fatty acids. Gil-C18 monoalkyl benzene sulfonic acids, and612*(318 straight-chain monoalkyl sulfuric acids.

The ammonium salts of saturated Cir-C13 fatty acids, CQ-Cia monoalkylbenzene sulfonic acids and C12-C1a straight-chain monoalkyl sulfuricacids can also be obtained by reacting asalt of the primary amine, e.g., a hydrochloride, a for mate, or an acetate, with a water-solubleinorganic salt of a fatty acid, an alkyl benzene sulfonic acid, or analkyl sulfuric acid. In so doing a suitable solvent, e. g., ethanol,will be employed 55 to separate the phase containing ammonium salt,

dissolved in ethanol or other appropriate organic solvent, from thephase containing the watersoluble salt such as NaCl, NaOOCCI-h, and thelike.

To illustrate: A primary straight-chain C12-Cl8 fatty amine, e. g.,lauryl amine, may be melted together with an equimolar amount of ahigher 012-018 saturated fatty acid, such as myristic acid. In this casethe product will be N-n-dodecyl ammonium myristate. The same ammoniumsalt may be obtained by dissolving the aforementioned reactants inethanol or other appropriate inert solvent, and substantiallyevaporating the solvent medium.

In order to obtain the foam stabilizing salt of a C12 primary fattyamine and a C12 monoalkyl benzene sulfonic acid, the amine is reactedwith the sulfonic acid and yields the desired ammonium salt. One mayalso obtain this salt by reacting a hydrochloride of the amine, e. g.,octadecyl amine hydrochloride, with sodium monoalkyl benzene sulfonatein ethanol as a solvent medium. Sodium chloride is precipitated, and,upon filtering and evaporating the alcohol, the desired octadecylammonium sulfonate additive is recovered. Salts of 012-018 fatty aminesand alkyl sulfuric acids may be prepared in a similar manner. Forinstance, a salt of the primary amine, e. g., N-n-tetradecyl ammoniumacetate, can be reacted with an alcohol sulfate, e. g., sodium dodecylsulfate, and, upon separation of phases with the aid of a suitablesolvent, will yield the desired foam-promoting and foam-stabilizingadditive, namely, N-n-tetradecyl ammonium alkyl sulfate.

In addition to the surface-active alkyl sulfates and the foam promotingalkyl ammonium salt additives, the detergent compositions of theinvention may contain builders conventionally employed in conjunctionwith anionic detergents such as inorganic sulfates, phosphates andsilicates, extenders such as sodium carboxymethyl cellulose, opticalbleaches, perfumes, etc. These additives are employed in amounts readilydeterminable by those skilled in the art to suit the requirements ofeach particular formulation. Ordinarily, aqueous solutions (in 0.1 to0.4% concentration) of detergent compositions which contain in each 100parts by weight from to 50 parts of the surface-active ingredient, thebalance being the aforementioned inorganic builders and otherconventional additives, will produce good, stable foam upon addingthereto from 0.5 to 10% by weight of the foam-promoting ammonium salt.

In heavy-duty, all-purpose detergent compositions generally containingfrom 15 to 30 parts of the surface-active ingredient in each 100 partsof solid constituents, from about 0.5 to 5% by weight, and preferablyfrom 1.0 to 2.5% by weight, of the foam-promoting ammonium salt providesthe desired effect.

I have furthermore found that salts of C12-C22 straight-chain alkylsulfuric acids which constitute the principal surface-active ingredientof my improved detergent compositions may be replaced in part bycompatible water-soluble salts of (la-C18 monoalkyl benzene sulfonicacids, and preferably C12-C15 monoalkyl benzene sulfonic acids. So longas at least of the combined weight of surface-active ingredients in suchmodified composition is constituted by the water-soluble C12-C22 alkylsulfate, the foam characteristics will be improved by the introductionof from about 0.5 to about 10% by weight of the ammonium salt additivein accordance with the invention. This til represents an importantfinding, since the fatty alcohols reported in the art as suitable agentsfor improving the foaming characteristics of alkyl sulfate detergentsare ineffective in detergent compositions containing alkyl benzenesulfonate as the only surface-active ingredient. Furthermore, salts offatty amines and organic acids, disclosed in the present specificationas effective additives for improving the foaming characteristics ofalkyl sulfates are likewise inefficient in detergent compositions wherean alkyl benzene sulfonate is the sole surface-active constituent.

A number of tests was carried, out with the various formulationsprepared in accordance with my invention and their results were comparedwith the results obtained employing other known compositions of thetrade. Stock solutions for these tests were prepared, using a smallamount of isopropanol, and heating if necessary, to dissolve a sample ofthe detergent formulation in order to obtain a 5% solution in distilledwater. In a representative test series the composition contained 24% byweight of total surface-active ingredients, including the foam-promotingammonium salt; 55% of sodium tripolyphosphate; and 21% of sodiumsulfate. By dissolving 20 g. of such a. 5% solution in 500 ml. of warmwater to F.) in a 2 liter beaker, a 0.2% solution was obtained foractual use in the tests.

The tests were carried out in accordance with the following technique:The test solution was agitated vigorously for 1 minute (with the aid ofa mechanically driven propeller stirrer) and then allowed to stand foran additional 1 minute, whereupn the foam height in millimeters wasmeasured. Heights of more than 30 mm. were rated as high; heightsbetween 20 to 30 mm. were rated as medium; and those of less than 20 mm.were rated as low. Fifteen minutes after the agitation was terminated,the foam heightwas measured again, and the stability and quality of thefoam were ascertained.

The foam stability was rated by blowing on a small volume of foam gentlywith air. In the case of unstable foam, this procedure resulted in arapid decay (collapse) of foam bubbles. The quality of the foam, 1. e.,the size of the foam bubbles and the feel, or body, of the foam, wasrated by comparing them with the foams produced by two formulations:detergent composition A which contains 10% by weight of sodium C12-C14alkyl sulfate, 50% by weight of sodium tripolyphosphate, 10% by weightof sodium C12- C15 alkyl benzene sulfonate, 2% by weight of laurylalcohol, the balance to make 100% being Nazsoi builder; and detergentcomposition B which contains 24% by weight of sodium ClZ-Cl5 alkylbenzene sulfonate; 55% by weight of sodium tripolyphosphate and 21% byweight of NazSO. builder. Composition A produces excellent creamy, smallsize foam bubbles and a heavy stable dense-bodied suds and its foamstability and quality are, therefore, rated to be Good. Composition Bproduces lacy, rapidly collapsing foam, and its foam quality andstability are rated Poor. The designation Fair is employed in thespecification to rate those foams approaching the stability and qualityof the foam formed by composition A.

The experimental data obtained by the aforedescribed evaluationtechnique clearly show that the addition of salts of primary fattyamines and organic acids described hereinbefore to the anionic detergentcompositions containing straightchain (ha-C22 alkyl sulfates provides animproved foam and stabilizes this foam, rendering these detergentcompositions attractive for the user.

The following Table I contains the results of a few representative testsselected from the extensive experimental data to illustrate theadvantages attained by the detergent compositions of the presentinvention. In this table, the amounts of the foam-promoting additive aregiven in per cent of the total Weight of surface-active and inertingredients of the detergent composition which contained (except whereotherwise indicated) 20% of surface-active materials, 55% of sodiumtripolyphosphate and 25% of sodium sulfate builder. The surface-activeportion of the composition in all tests (except where otherwiseindicated) contained. of sodium 012-015 monoalkyl benzene sulfcnate,from 1 to 2% of the foam-promoting ammonium salt, the balance beingsodium Chi-C18 straight-chain alkyl sulfates produced by sulfonation ofa blend of C14- C18 alcohols, derived in turn by catalytic hydrogenationfrom the higher fatty acids (or esters thereof) present in tallow.

The foam heights are designated by H-high, M-medium, L-low; foamstability and foam quality are designated by G-good, F-fair and P-poor.The sodium alkyl benzene sulfonate was prepared in accordance with thedescription of U. S. Patent No. 2,477,383 to A. H. Lewis, by sulfonationof 012-015 polypropylene benzene. The concentration of test solutionswas 0.2%, cmploying tap water of 5c p. p. m. hardness CaCOs; A; MgCOs)TABLE I Foam evaluation data [Concentration of Solution: 0.2% in TapWater] effective for this purpose, as may be seen on the example oftertiary dodecyl anilinium salt of Test #16.

Furthermore, the tests have shown that the primary straight-chain fattyamine must be first reacted with the appropriate organic acid from theparticular group of operative fatty, alkyl benzene sulfonic and alkylsulfuric acids, and only then the resulting salt should be introducedinto the mixture of surface-active and inert ingredients. Incontradistinction to a practice proposed for cationic detergents, theintroduction of N-nalkyl amine, as shown in Test #15 of the table,brings no improvement of foam properties.

Simultaneously with the aforedescribed foam tests, a number of foamsamples, produced by detergent compositions containing the ammonium saltadditive in accordance with the invention, were tested by letting thesuds slide down a vertical glass surface. All of the samples slid downrapidly, indicating a high degree of desirable wetness.

As mentioned hereinbefore, the presence of the foam-promoting ammoniumsalts of my invention does not affect adversely the detergencycharacteristics of the anionic alkyl sulfate detergent compositionscontaining these salts. Frequently their presence appears, in fact, tobe beneficial with respect to detergency. A series of tests were carriedout by employing a conventional automatic agitator-type washing machine.The solutions employed were those of detergent compositions, prepared inaccordance with the Amount Name of Additive of Addi' Comparative FoamHeights Foam Foam tive in percent After 1 min.

After 15 min.

Stability Quality N-n-dodecyl ammonium laurate Same Same n Nn-dodecylammonium palmitate Salt of primary n-dodecyl amine and 014-0 3 tallowfatty acids.

Same

Salt of primary Cn-Cm alkyl amine,

and G14-C13 tallow fatty acids.

N-n-dodecyl ammonium 012015 alkyl benzene sulfonate.

Salt of primary 012-0 0 alkyl amine and 012411 alkyl benzene sulfonicacids.

N-n-octadecyl ammonium laurate Salt of primary alkyl amine and fattyacids, both derived from tallow.

Same

N-ntetradecyl ammonium salt of a mixture of 0 2-0 alkyl benzene sulfonicand CLPCIB alkyl sulfuric acids.

N-n-dodecyl amine Tcrtdodecyl anilinium laurate N-n-dodecyl ammonium 3myristate...-

[Obmore N) M NH NH-H-INHM F IE EH 1 III I I i H I i -H HIH IMEI PMN FiU1 K 1 mm mmmmmm Wd Q Q Qn QQQQQQ Q Q Q@ QQ DQQQ gtt mo e (we e 1Primary amine derived from a mixture of coconut fatty acids.

2 Formed by reacting N-n-tetradecyl ammonium acetate with a mixture ofbenzene Sulfonates and sodium (314-018 alkyl sulfates.

sodium 0 2-015 alkyl 3 Added to a detergent composition containing: 8%by weight of sodium stearyl sulfate, 12% by weight of sodium 012-015alkyl benzene sulfonate, by Weight of sodium tripolyphcsphate, 21%

by weight of sodium sulfate.

invention and containing 9% by weight of sodium salts of Cli-Cifi alkylsulfuric acids derived from tallow; 10% by weight of sodium salts ofUri-C15 alkyl benzene sulfonic acids, produced in accordance with thetechnique described in U. S. Patent No. 2,477,383 to A. H. Lewis; 1% byweight of the foam-promoting ammonium salt additive of the invention;55% by weight of sodium tripolyphosphate builder; and 25% by weight ofsodium sulfate builder. Comparison tests were made with a solution ofthe previously mentioned detergent composition A. The followingconcentrations were used: 0.1%, 0.15% and 0.2% in hard water (300 p. p.m.=200 p. p. m. a0Os+100 p. p. m. lvIgCOs) and 0.15% in soft water (50p. p. m.; 0aCO3:Mg0Oa=-2:1). The machine in each test received a load of6 pounds of clean cotton towels, having pinned thereto a strip or swatchof cotton, uniformly soiled with a paste of oil, tallow and carbonblack. The temperature of the wash solutions was about 140 F., and eachtest consisted of one washing of 20 minutes duration followed by two-minute rinses. On completion of each test the swatches were removed,and the degree of whiteness obtained was measured in a photoelectricapparatus, free of human equation. The detergency was rated withreference to an arbitrarily chosen detergency standard, namely, thewhiteness level secured with the 0.4 concentration of a well-known fattyacid soap in hard water (300 p. p. m), and taken to be equal to 100.

The results of the aforementioned test runs are tabulated in thefollowing Table II:

The actual preparation of the detergent compositions of my inventionpresents no difficulties. The only condition precedent for thepreparation of these compositions is that the foampromoting ammoniumsalt be prepared first and then only blended with the mixture ofsurfaceactive and inert ingredients, since, as it was shown, directaddition of primary amine to the detergent composition is ineffective.Blending with the detergent slurry and drying of the blended product arecarried out in the conventional manner. The blended slurry may be workedup by spray-drying or drum-drying to give a particulate, flake or chipproduct, or it may be processed into a paste, or yet may be diluted andsold as a liquid concentrate.

It is to be understood that the aforegiven description and examples aremerely illustrative of the invention, and that all modificationsconsistent with the spirit and scope thereof are included within theterms of the following claims.

I claim:

1. A detergent composition comprising as its surface-active ingredient awater-soluble salt of an alkyl sulfuric acid, having in its molecularstructure a straight-chain alkyl radical containing from 12 to 22 carbonatoms, and a minor amount of a salt of a primary Cl2-C18 straight-chainalkyl amine and an organic acid from the group consisting of 012-018saturated fatty acids, 011-018 monoalkyl benzene sulfonic acids and012-018 monoalkyl sulfuric acids, said amount being sufiicient to impartstability to the foam of dilute aqueous solutions of said detergentcomposition of concentrations in the range from 0.1 to 0.4%.

2. A detergent composition, each 100 parts by weight whereof containsfrom 10 to 50 parts of surface-active ingredients constituted by awater-soluble salt of a straight-chain 012-022 alkyl sulfuric acid, andfrom about 0.5 to about 1.0%, based on the weight of solid ingredientsin said detergent composition, of a salt of a primary CHI-C18straight-chain alkyl amine and an organic acid from the group consistingof 012-016 saturated fatty acids, 09-018 monoalkyl benzene sulfonicacids and 012-0111 monoalkyl sulfuric acids.

3. A detergent composition, each 100 parts by weight whereof containsfrom 15 to 30 parts of surface-active ingredients present as a mixtureof water-soluble salts of a 012-022 straight-chain alkyl sulfuric acidand of a 011-018 monoalkyl benzene sulfonic acid, at least 25% of thetotal weight of these surface-active ingredients being constituted bysalts of said alkyl sulfuric acid, said detergent composition furthercomprising from about 0.5 to about 5% by weight, based on the totalweight of solid ingredients therein, of a salt of a primary C12-C18straightchain alkyl amine and an organic acid from the group consistingof ClZ-CIB saturated fatty acids, C9Cl8 monoalkyl benzene sulfonic acidsand C12-C18 monoalkyl sulfuric acids.

4. A detergent composition, each 100 parts by weight whereof containsfrom 15 to 30 parts of surface-active ingredients present as a mixtureof water-soluble salts of a 012-022 straightchain alkyl sulfuric acidand of a C9C18 monoalkyl benzene sulfonic acid, at least 25% of thetotal Weight of these surface-active ingredients being constituted bysalts of said alkyl sulfuric acid, said detergent composition furthercomprising from about 1.0 to about 2.5% by weight, based on the totalweight of solid ingredients therein, of a salt of a primary C12-C18straightchain alkyl amine and an organic acid from the group consistingof 012-013 saturated fatty acids, 09-011 monoalkyl benzene sulfonicacids and ClZ-C18 monoalkyl sulfuric acids.

5. A detergent composition containing in each 100 parts thereof from 15to 30 parts by weight of surface-active water-soluble salts of a 012-022straight-chain alkyl sulfuric acid and of a 012-015 monoalkyl benzenesulfonic acid, at least 25% of the total weight of said surface-activeingredients being constituted by salts of said alkyl sulfuric acid, saiddetergent composition further containing from to '70 parts by weight ofinorganic alkali metal builders, and from 1.0 to 2.5%, based on thetotal weight of the solid constituents in said detergent composition, ofa salt of a primary 012-0111 straight-chain alkyl amine and an organicacid from the group consisting of C12-C18 saturated fatty acids, 09-018monoalkyl benzene sulfonic acids and ClZ-CIB monoalkyl sulfuric acids.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,226,118 De Groote Dec. 24, 1940 2,256,877 Bertsch Sept. 23,1941

2. A DETERGENT COMPOSITION, EACH 100 PARTS BY WEIGHT WHEREOF CONTAINSFROM 10 TO 50 PARTS OF SURFACE-ACTIVE INGREDIENTS CONSTITUTED BY AWATER-SOLUBLE SALT OF A STRAIGHT-CHAIN C12-C22 ALKYL SULFURIC ACID, ANDFROM ABOUT 0.5 TO ABOUT 10%, BASED ON THE WEIGHT OF SOLID INGREDIENTS INSAID DETERGENT COMPOSITION, OF A SALT OF A PRIMARY C12-C18STRAIGHT-CHAIN ALKYL AMINE AND AN ORGANIC ACID FROM THE GROUP CONSISTINGOF C12-C18 SATURATED FATTY ACIDS, C9-C18 MONOALKYL BENZENE SULFONICACIDS AND C12-C18 MONOALKYL SULFURIC ACIDS.